A recent update from the Soybean Cyst Nematode (SCN) Coalition highlights troubling new findings regarding the spread of SCN across North America. Between 2020 and 2023, SCN was reported for the first time in 31 counties across 10 U.S. states, while in Canada, the pest appeared in 10 rural municipalities in Quebec and three counties in Manitoba and Ontario.
The data is presented on a map, which shows the distribution of SCN in the U.S. and Canada. Newly reported infestations, confirmed between 2020 and 2023, are marked in blue, while previously identified areas are shown in red. This updated map emphasizes the increasing prevalence of SCN, which continues to spread despite ongoing efforts to manage it.
Greg Tylka, director of the Iowa Soybean Research Center at Iowa State University, has been tracking the distribution of SCN for years and provides a sobering outlook on its impact. According to Tylka, SCN is present in every county across Iowa, with 70% to 75% of the state’s fields showing signs of infestation.
“I tell my farmers there’s a three out of four chance that any field they plant soybeans in has SCN,” Tylka said. “Probably only Illinois has more widespread numbers of the pest.”
SCN-Free State
The spread of SCN is a growing concern in the U.S. soybean industry. Every state that produces soybeans has reported some level of SCN infestation, with one notable exception: West Virginia. According to the SCN Coalition, this state remains the only one where SCN has not yet been detected.
A Major Contributor to Yield Loss
SCN is the primary cause of soybean yield loss in the U.S., costing an estimated $1.2 billion annually. For farmers, this translates to significant financial losses, often resulting in a reduction of 10 to 30 bushels per acre, depending on factors such as soybean variety and weather conditions.
Despite the widespread impact, Tylka notes that many U.S. farmers still do not regularly test their fields for SCN. He points out that many farmers are hesitant or unwilling to address the issue, citing a range of excuses for avoiding testing.
“I’ve heard lots of excuses about not looking for it, lots of rationalizations,” Tylka said. “Farmers are way better off to know they’ve got it, because they can then adopt management practices to keep it under control and prevent further spread.”
Strategies for Managing SCN
To mitigate the spread of SCN and limit its impact on yield, the SCN Coalition urges farmers to take a proactive approach. The group recommends working with agronomic advisers to implement strategies such as:
- Testing fields to identify SCN presence and population levels
- Rotating resistant soybean varieties with PI 88788 and Peking genetics
- Incorporating non-host crops into crop rotations
- Considering nematode-protectant seed treatments
The Coalition has also developed the SCN Profit Checker tool, which allows farmers to assess the financial impact of SCN on their fields. Powered by data from over 25,000 university research plots, this online tool helps growers quantify the economic losses attributed to SCN infestation.
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